chr5-112840507-T-C
Variant summary
Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_ModerateBP6
The NM_000038.6(APC):āc.4913T>Cā(p.Met1638Thr) variant causes a missense change. The variant allele was found at a frequency of 0.0000266 in 1,614,138 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M1638I) has been classified as Uncertain significance.
Frequency
Consequence
NM_000038.6 missense
Scores
Clinical Significance
Conservation
Publications
- classic or attenuated familial adenomatous polyposisInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
- desmoid tumorInheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp
- familial adenomatous polyposis 1Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics
- gastric adenocarcinoma and proximal polyposis of the stomachInheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet
- sarcomaInheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
- APC-related attenuated familial adenomatous polyposisInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Turcot syndrome with polyposisInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Cenani-Lenz syndactyly syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Likely_benign. The variant received -3 ACMG points.
Transcripts
RefSeq
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| APC | ENST00000257430.9 | c.4913T>C | p.Met1638Thr | missense_variant | Exon 16 of 16 | 5 | NM_000038.6 | ENSP00000257430.4 | ||
| ENSG00000258864 | ENST00000520401.1 | n.228+11535T>C | intron_variant | Intron 3 of 7 | 3 | ENSP00000454861.1 |
Frequencies
GnomAD3 genomes AF: 0.0000131 AC: 2AN: 152160Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000159 AC: 4AN: 251184 AF XY: 0.0000221 show subpopulations
GnomAD4 exome AF: 0.0000280 AC: 41AN: 1461860Hom.: 0 Cov.: 65 AF XY: 0.0000330 AC XY: 24AN XY: 727232 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000131 AC: 2AN: 152278Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1AN XY: 74460 show subpopulations
ClinVar
Submissions by phenotype
Hereditary cancer-predisposing syndrome Uncertain:1Benign:1
This missense variant replaces methionine with threonine at codon 1638 of the APC protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. In a large colorectal cancer case-control study, the variant has been reported in 32/12503 cases & 70/23705 controls (PMID: 33309985). This variant has been identified in 4/251184 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
Familial adenomatous polyposis 1 Uncertain:1
This sequence change replaces methionine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 1638 of the APC protein (p.Met1638Thr). This variant is present in population databases (rs201797422, gnomAD 0.006%). This missense change has been observed in individual(s) with colorectal cancer (PMID: 33309985). ClinVar contains an entry for this variant (Variation ID: 231898). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt APC protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Classic or attenuated familial adenomatous polyposis Uncertain:1
This missense variant replaces methionine with threonine at codon 1638 of the APC protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. In a large colorectal cancer case-control study, the variant has been reported in 32/12503 cases & 70/23705 controls (PMID: 33309985). This variant has been identified in 4/251184 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
APC-related disorder Uncertain:1
The APC c.4913T>C variant is predicted to result in the amino acid substitution p.Met1638Thr. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.011% of alleles in individuals of East Asian descent in gnomAD. In ClinVar, this variant is interpreted a likely benign/uncertain (https://www.ncbi.nlm.nih.gov/clinvar/variation/231898/). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
not specified Benign:1
Variant summary: APC c.4913T>C (p.Met1638Thr) results in a non-conservative amino acid change in the encoded protein sequence. Two of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 2.7e-05 in 1614138 control chromosomes, predominantly at a frequency of 0.0008 within the East Asian subpopulation in the gnomAD database. The observed variant frequency within East Asian control individuals in the gnomAD database is approximately 11.2 fold of the estimated maximal expected allele frequency for a pathogenic variant in APC causing Familial Adenomatous Polyposis phenotype (7.1e-05). c.4913T>C has been reported in the literature in numerous individuals affected with colorectal cancer but also in an approximately equal portion of the healthy control cohort (example, Fujita_2022), with no strong evidence for causality. These report(s) do not provide unequivocal conclusions about association of the variant with Familial Adenomatous Polyposis. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 33309985). ClinVar contains an entry for this variant (Variation ID: 231898). Based on the evidence outlined above, the variant was classified as likely benign. -
APC-Associated Polyposis Disorders Benign:1
This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at